Method and apparatus for fabricating jointed structures



J. CEDAR Sept. 15, 1970 METHOD AND APPARATUS FOR FABRICATING JOINTED STRUCTURES Filed April 26, 1968 5 Sheets Sheet 1 lA/Vi/VTOA METHOD AND APPARATUS FOR FABRICATING JOINTED STRUCTURES Filed April 26, 1968 J. CEDAR Sept. 15, 1970 5 Sheets-Sheet 2 Q) S! IVVV4EZA ITII? JACK CEDAR M\ m m bwi w? *3 mm United States Patent US. Cl. 29-434 11 Claims ABSTRACT OF THE DISCLOSURE A method for fabricating or assembling jointed structures having a housing containing therein at least an end of a cooperating linkage, intended to be movable relative to the housing, and a closure or retainer member employs the steps of providing a first relatively high loading force against the housing, linkage end and retainer in order to seat at least the linkage end against a seating surface carried by the housing, reducing the first loading force and applying at least a second relatively low loading force against the same components and working the material of at least the housing so as to hold the retainer in a prescribed position relative to the housing and the linkage end in order to provide for a certain degree of relative movement between the linkage and housing.

An apparatus for performing the above method has a clamping rod positioned by pressure responsive means so as to apply the said first loading force against the housing, linkage end and retainer and then to apply said second relatively low loading force thereto during which time a rotating spindle provided with a metal-forming tool is lowered by pressure responsive means against the workpiece, comprised of at least said housing, so as to work the material comprising the workpiece to hold the retainer in a prescribed relationship relative to the housing and linkage.

BACKGROUND OF THE INVENTION It was found that, in the past, jointed structures when assembled by some metal-deforming process such as, for example, spinning, coining, or rolling over flange portions, produced jointed assemblies which were not only inconsistent in performance but also would result in having the assembled components, which comprised the jointed assembly, become so loose with respect to each other as to preclude the use of suchjointed structures.

Attempts to correct this condition by applying a heavy preload to the components of the jointed structure during, for example, the spinning or rolling-over cycle did not prove to be successful. The resulting jointed structures were found to have their components so tightly engaged with each other as to again preclude their use for the intended purposes.

Attempts to gradiently reduce and find a particular magnitude of preload were totally unsuccessful because such jointed structures would continue to be too tight and then with progressively reduced preloads suddenly become too loose. In other words, no happy medium for a value of preload could be found.

SUMMARY OF THE INVENTION The present invention resides in a method of fabricating jointed structures and in apparatus for carrying out the inventive method. I

The method comprises the steps of applying a first force of a predetermined magnitude against the components comprising the jointed structure, applying to the exclusion of said first force a second force of a predetermined magnitude less than the magnitude of said first force against the said components comprising the jointed structure, and

3,528,161 Patented Sept. 15,, 1970 ice then forming the material of at least one of the components comprisnig the structure while said second force is being applied in order to retain said components in a prescribed assembled relationship to each other.

Accordingly, an object of this invention is to provide a method of fabricating assembled jointed structures in a manner whereby the components comprising the jointed structure will neither be too loose or too tight with respect to each other.

Another object of this invention is to provide apparatus capable of automatically performing the prescribed steps in a manner whereby a jointed structure in accordance with the above object can be achieved.

Other specific objects and advantages of this invention will become apparent when reference is made to the following description considered in conjunction with the drawings.

DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. 1 is a front elevational view of an apparatus for carrying out the inventive method herein disclosed;

FIG. 2 is a fragmentary cross-sectional view taken generally on the plane of line 22 of FIG. 1 and looking in the direction of the arrows;

FIG. 3 is a schematic diagram of pneumatic circuitry employed in association with the apparatus of FIGS. 1 and 2;

FIG. 4 is an enlarged view, partially sectioned, of a portion of the apparatus disclosed in FIGS. 1 and 2; and

FIG. 5 is a schematic wiring diagram illustrating electrical circuitry associated with the apparatus of FIGS. 1 and 2 and the pneumatic circuitry of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in greater detail to the drawings, Fig. 1 illustrates a machine 10, constructed in accordance with the invention, comprising a base 12, situated as on a floor surface 14, supporting a machining table 16 on which a fixture 18 is securely mounted by and suitable means such as clamps or bolts (not shown). A machine column 20 carries a support 22 for the spindle assembly and advance mechanism as well as a second support 24 for the spindle drive pulley or sheave 26. A superstructure-like support assembly 28 comprised of vertical plates 30 and 32, secured to the machine at opposite sides thereof, a vertically extending back plate 34 joining plates 30 and 32, and first and second generally laterally extending plates 36 and 38 respectively supporting a pneumatically operated piston and cylinder assembly 40 and a shaftengaging bushing 42. Gussets 44 and 46 may be provided for reinforcing support plate 36. If desired, the entire support assembly 28 may be of Welded construction and side plates 30 and 32 may be secured to the machine frame or column by any suitable means such as screws (not shown).

Pneumatically operated piston and cylinder assemblies 48 and 50 suitably pivotally secured to the opposite sides of the machine frame or column 20 by support brackets 52 and 54, each have their pistons operatively connected, as by means of piston rods 56 and 58, to levers 60 and 62 which, in turn, are connected to rotatable driving hubs 64 and 66. The hubs 64 and 66 are suitably drivingly engaged with a rotatable shaft or shafts 68, generally transversely disposed to the centerline of the spindle assembly 70, and extends through a feed gear 72 in a manner so as to cause rotation of the feed gear 72 corresponding to the rotation of the hubs 64 and 66 caused by the piston assemblies 48 and 50 as also illustrated in FIG. 2. As shown in both FIGS. 1 and 2, the piston rods 56 and 58 are preferably connected to axially adjustable yoke extensions 74 which are respectively pivotally connected to levers or arms and 62. An operators control panel, illustrated generally at 76, may be secured to and carried by the machine .frame or base 12. Further, a source 78 of pneumatic pressure having a supply conduit 80 is operatively connected, in a manner to be described, to conduits 82, 84 and conduits '86, 88 of cylinder assemblies 40, 48 and 50, respectively, in order to supply pneumatic pressure thereto in a prescribed fashion.

Referring in greater detail to FIG. 2, it can be seen that an electric motor 90, having electrical leads 92, 94 and 96, is suitably supported on the machine column or frame 20 in a manner so as to present sheaves 98 and 100', (of different respective diameters) connected to motor shaft 102, in functional alignment with the grooves of spindle sheave 26. Suitable motion transmitting belts 104 engage sheave 26 and one or the other of sheaves 98 and 100.

Spindle sheave 26 is suitably mounted on support 24 and drivingly connected to a sleeve-like bearing 106 journaled for rotation within support 24. Bearing 106 is internally splined, as indicated at 108, so as to engage externally formed splines 110 on spindle shaft 112. Such a splined connection provides for a rotatable driving connection therebetween while permitting axial movement of the spindle shaft 112 relative to the bearing 106.

Spindle shaft 112 may be provided with a general shoulder-like bearing portion 114 situated so as to be generally contained within the spindle feed bearing 116 and cooperating cap or retainer 118 suitably secured thereto. The spindle feed bearing 116, precluded from angular rotation, is provided with a gear-engaging rack 120 which is engaged by feed gear 72. Accordingly, as feed gear 72 is either rotated clockwise or counter-clockwise by piston assemblies 48 and 50, the spindle feed bearing 116 causes corresponding upward or downward movement of spindle shaft 112. The lower end of spindle shaft 112 has a spinning assembly 122 suitably secured thereto. A plurality of spinning heads or rollers 124, 126 carried by cooperating shafts 128 and 130 journaled in the spinning head 132 are adapted to engage the workpiece, carried by the fixture 18, in order to perform one step of the overall method disclosed herein.

Piston 134, of cylinder assembly 40, is operatively connected, as by the piston rod 136, to a force transmitting rod 138 which may be joumaled near its upper end in bushing 42 and journaled at its lower end within spindle shaft 112. An adjustable connection as generally indicated at 140 may, of course, be provided between the piston rod 136 and force rod 138.

The workpiece 142 and spinner assembly 122 is illustrated in greater detail in FIG. 4 wherein the fixture 18 is shown generally containing and holding the workpiece 142 which may be comprised of an outer housing 144 having an internally formed seat 146 of a spherical contour against which is urged the ball end 148 of a connecting link 150. A cover member 152 is placed within the open end 154 of housing 144 in a manner urging a compression spring 155 against the ball end 148. The other end 156 of link 150 extends through a second opening 158 formed in housing 144. The fixture 18 may be provided with suitable stop or abutment means such as a pin 160 adapted to engage an arm portion 162 of the workpiece 142 in order to prevent undue rotation of the workpiece during the assembling operations performed thereon.

It should be mentioned at this time that the spinner assembly 122 and a portion of the workpiece 142have been illustrated under two conditions. That is, that portion of spinner body 132 shown to the right of centerline 164 and in cross-section depicts the position of the spinner roller 126 upon initial engagement with the upper endsurface of workpiece housing 144. Also, that portion of the housing 144 generally to the right of centerline 164 also depicts the configuration of the housing 144, in the area of cover 152, at the time of initial contact by roller 126. Even though this is shown with reference to only 4 roller 126, it applies equally well to all of the spinner rollers within the spinner assembly 122 whether there be two, three or more spinner rollers. That is, each of the spinner rollers would engage the workpiece in the manner typically illustrated by roller 126.

Further, that portion of the spinner body 132 to the left of centerline 164 and partially in cross-section, depicts the position of the spinner roller 124 upon completion of the spinning operation performed on the workpiece housing 144. Also, that portion of the housing 144 generally to the left of centerline 164 depicts the configuration of the housing 144, in the area of cover 152, at the time of completion of the spinning operation. Even though this is shown Wtih reference to only roller 124, it applies equally well to all of the spinner rollers within the spinner assembly 122 whether there be two, three or more spinner rollers. That is, each of the spinner rollers would, upon completion of the spinning operation, assume the position typically illustrated by spinner roller 124.

As further illustrated by FIG. 4, spinner roller 126 is carried by a shaft 130 which in turn is both rotatable and axially movable within a guide way 166 formed within spinner head 132 in a manner so as to be angularly disposed with respect to centerline 164, which is the centerline of rotation of spinner assembly 122. Preferably, a compression spring 168 is contained between a suitable spring perch 170 and the end 172 of shaft 130. The arrangement discussed above with respect to spinner roller 126 and shaft 130 is typical and applies to the other spinner rollers of which roller 124 would be one.

A passageway 174 is formed through body 132 in order to permit the free axial and angular movement between rod 138 and spinner head 132.

Generally, with the clamping rod or bar 138 maintaining the components of the workpiece in the prescribed positions, the spindle assembly is moved downwardly causing the spinning assembly 122 to be downward, while undergoing rotation, until the shoulder-like surfaces 176 of rollers 126 and 124 engage upper end surface 178 of housing 144. At this time the extending somewhat cylindrical surfaces 180 of the rollers are brought into close proximity or juxtaposition with the outer side surface of workpiece housing 144.

As the spindle assembly 70 and spinner head 132 is moved further downwardly from the initial contact position represented by line 182 to the position depicted by line 184 (the distance, X) representing the completion of the spinning operation, rollers 124 and 126 are, by virtue of shoulders 176, precluded from any further downward movement. Therefore, in order to compensate for this, the rollers 124 and 126 urge their respective shafts 128 and 130 upwardly, relative to body 132, within guides 166. In so doing, the net effect is to cause the rollers and cylindrical surfaces 180 to move toward each other thereby compressing and cold working the metal (or other material forming housing 144) engaged by surfaces 180. Consequently, the metal is worked and flowed radially inwardly so as to generally envelop the periphery of the cover 152 as illustrated at 186 and 188.

Before referring specifically to FIGS. 3 and 5, it might be best to first describe the overall operation of the machine thus far described in order to clearly set forth the method of operation on which the machine is based.

As previously stated, it was found that jointed structures when assembled by some metal-deforming process such as, for example, spinning, coining or rolling over flange portions, produced jointed assemblies which were not only inconsistent in performance but also would result in having the assembled components become so relatively loose with respect to each other as to preclude the use of such jointed structures. Attempts to correct this by applying a heavy preload to the components of the jointed structure during, for example, the spinning cycle did not prove to be successful. The resulting jointed structures would have their components so tightly engaged with each other as to again destroy their use for the intended purposes. Attempts to gradiently reduce and find a particular value for the preload were totally unsuccessful since such jointed structures would continue to be too tight and then with progressively reduced preloads sudenly become too lose. In other words, there could be found no happy medium for a value of preload.

It was then discovered that a particular method of assembly produced, with predictable repeatability, jointed assemblies or structures of desired characteristics without such structures being too tight or becoming too loose. The machine 10, thus far disclosed is based on such a method.

The method of operation can be generally described as follows:

(A) first, an initial relatively heavy preload of predetermined force is applied to the components comprising the jointed structure;

(B) second, the initial preload is reduced in value until a second preload of a second predetermined force is attained and the second preload is maintained against the components of the structure;

(C) the metal or other material of the workpiece is worked so as to maintain the components in the prescribed positions; and

(D) all preload is removed and the finished jointed assembly removed from workpiece holder.

Even though not completely certain, it is nevertheless believed that the multiple-stage application of a preload force first tends to seat the components relative to each other thereby eliminating, to a great extent, any slight high spots or imperfections in mating or contacting surfaces. Once this is done, the subsequent preload of lesser magnitude is better able to establish the degree of tightness required in the jointed structure and maintain that condition while the components are being suitably secured to each other as by any suitable method of joining or connecting the containing-components.

In the machine 10, of FIGS. 1, 2 and 3, embodying the invention, cylinder assembly 40 and rod or shaft 138 combine to apply the preloads and perform the clamping function while the spinning assembly including spinner rollers 124 and 126 serve to perform the function of joining the cover 152 and outer housing 144 into a jointed structure.

FIG. 3 is a schematic diagram of the neumatic circuitry employed in combination with the basic structure of machine in order to enable selective operation of the machine in either the manual or automatic mode of operation. For purposes of simplicity and clarity, cylinder assemblies 48 and 50 are represented by a single schematically depicted cylinder assembly identified at 50. If a plurality of cylinder assemblies such as 48 and 50 were to be employed, conduits 88 of both cylinder assemblies as well as conduits 86 of both cylinder assemblies would, respectively, be connected in parallel.

Still referring to FIG. 3, it can be seen that the source 78 of pneumatic pressure has an output supply conduit 80 to which are connected branch conduits 200, 202, 204 and 206 which respectively lead to an air-solenoid valve' assembly 208, and adjustable regulator valve assemblies 210, 212 and 214. Pressure gauges 216, 218 and 220 may be placed in the conduits 222, 224 and 226 respectively leading from the other sides of regulators 210, 212 and 214. In one successful embodiment of the invention regulators 210, 212 and 214 were each Rego brand regulators model No. 88036.

Conduit 222 leads to a second solenoid valve assembly 228 which, in turn communicates with a selector valve assembly 230 by means of a conduit 232. (It has been found that a Valvair brand selector valve model No. B2152V or the equivalent performs the functions desired of selector valve assembly 230.) Similarly, conduit 224 communicates between selector valve 230 and regulator 212. An inspection of selector valve 230 discloses branch conduits 234 and 236 respectively connected to conduits 232 and 224. The purpose of these branch conduits is to shift the valve member 238 to either the left or right so as to respectively connect conduit 224 to conduit 240 or conduit 232 to conduit 240 if the pressure in conduit 224 is greater than that in conduit 232 or if the pressure in conduit 232 is greater than that in conduit 224. In the position illustrated, conduit 82 is vented to the atmosphere or some other relatively low reference pressure. However, when valve member 242 of solenoid valve assembly 208 is moved to the right, conduit 82 is placed in communication with supply conduit 240 while conduit 84 is vented to the atmosphere. A limit switch schematically illustrated at 244 is so positioned on the machine 10 that it is engaged and actuated upon sufficient downward movement of piston 134 and the clamping rod 138.

Conduit 226, communicating between regulator valve 214 and a third solenoid valve assembly 246, also contains a pressure switch 248; similarly, a second pressure switch 250 is placed in conduit 82 leading to clamping cylinder assembly 40. As with reference to solenoid assembly 208, in the position illustrated, conduit 88 is vented to the atmosphere or some other suitable relatively low reference pressure. However, when valve member 252 is moved to the right conduit 88 is placed in communication with supply conduit 226 while conduit 86 is vented to the atmosphere. Further, a second limit switch assembly schematically illustrated at 254 is so positioned on the machine 10 that it is engaged as by some of the related lever arms or linkages upon sutlicient downward movement of spindle assembly 112 as dictated by the movement of spindle feed piston 256 within cylinder assembly 50.

FIG. 5 illustrates a schematic wiring diagram of circuitry employed in combination with the machine of FIGS. 1 and 2 enabling both the manual and automatic operation of the said machine in accordance with the inventive method herein disclosed.

In the circuitry of FIG. 5, a source of electrical energy represented by conductors 300, 302 and 304 is adapted to be placed in circuit with conductors 92, 94 and 96 as by means of a manually operated gang switch 306. Conductors 92, 94 and 96, which lead to the spinner or spindle motor 90, respectively contain normally open relay operated contacts A308, A310 and A312.

A transformer 314 having its primary windings 316 connected to conductors 92 and 96, has its secondary winding 318 in circuit with conductor 320. Main conductors 322 and 324 are connected to conductor 320 and, in turn, have branch conductors or circuits therebetween. At this point, it should be noted that for purposes of clarity the various reference numerals for the relay coils and associated relay operated contacts are prefixed with the same alphabetical letter which permits mere visual inspection to see which contact is responsive to which relay coil. Further, a column of numerals within parenthesis are provided along the right side of the diagram. Such numbers will sometimes be employed along with reference numerals to indicate that that particular element may be located generally at the elevation of that particular number in parenthesis and laterally thereof.

Other main conductors 326 and 328 are respectively connected to conductor 320, on opposite sides of secondary winding 318, and, in turn, have conductors 330, 332, 334 and 336 connected thereto. Indicator lamps or lights 338 and 340 serially connected in conductor 330(1) provide a visual indication that conductor 320 has been energized and that the circuits are complete through fuses 342 and 344. Conductors 326 and 328 respectively contain normally open relay operated contacts B346 and B348 which are closed by a related relay B350 placed in circuit with conductor 352(6). The same relay B350 also serves to close normally open relay contacts B354 and 7 B356 respectively situated in series circuit with conductors 322 and 324.

Solenoid assemblies or windings 358, 360 and 362 are respectively placed in series circuit with conductors 332(2), 334(3) and 336(4) and as will become evident, are selectively energized to respectively control the positioning of the solenoid valve assemblies 208, 228 and 246 of FIG. 3.

Conductor 332 also has normally open relay operated contacts C364 and C366 in circuit therewith situated on opposite sides of solenoid 358 while conductor 336(4) has similarly positioned normally open relay operated contacts E368 and E370 which are operated by a relay coil E372 situated in series circuit with conductor 374(17).

Conductor 334(3), having one end connected to conductor 326 and its other end connected to conductor 332 at a point between solenoid 358 and relay contact C366, has a normally open relay contact D376 situated in series therewith and between conductor 326 and solenoid 360. Relay contact D376 is controlled by relay coil D378 serially connected in conductor 380(15) which, at times, is switched into circuit with conductor 382(14).

A conductor 384(5), connected between main conductors 322 and 324, has a first normally closed emergency stop switch 384 and a second power-start switch assembly 386 in series circuit therewith. Switch assembly 386, having switch members 388 and 390, may be of the type wherein switch member 388 is normally closed and switch member 390 is normally open. Accordingly, whenever the switch assembly 386 is pulled upwardly switch member 388 would remain closed while switch member 390 would be moved to a closed position. Conductor 384 further contains, in circuit therewith, a relay coil A392 which controls relay contacts A308, A310 and A312, in motor conductors 92, 94 and 96, as well as relay contact A394 which is in series circuit with conductor 352(6). As can be seen, conductor 352 is in parallel with a portion of conductor 384 so as to have one end connected to conductor 384 at a point generally between contacts or switch members 388 and 390, and the other end connected to conductor 384 at a point between relay coil A392 and main conductor 324. A branch conductor 396 is connected at one end to conductor 384, at a point between switch member 390 and relay coil A392, and connected at the other end to conductor 352 at a point between relay contacts A394 and relay coil B350. A second branch conductor 398, serially containing a lamp or light 400, has one end connected to conductor 384, between switch member 390 and relay coil A392, and another end connected to conductor 324.

A first pressure switch assembly 248 (also see FIG. 3) has a first switch member 404 in series circuit with a conductor 406(7) which also has, in circuit therewith, an indicator lamp or light 408 which signals the existence of low air pressure. A second switch member 410, operatively connected to switch member 404, is in circuit with a conductor 412(9). Pressure switch assembly 248 also contains contacts or switch members 414 and 416, operatively connected to each other, so as to have switch member 414 in series with conductor 412 while switch mem ber 416 is in series circuit with a conductor 418 containing a second signal lamp 420. Conductor 418 is in parallel with switch member 414 but in series with switch member 410.

Further, starting from the pressure switch assembly 248 and progressing to the right, conductor 412 sequentially contains a first palm button switch assembly 422, normally resiliently urged so as to have its switch member 424 closed, a second palm button switch assembly 426, normally resiliently urged so as to have its switch member 428 closed, a feed-spindle-actuated limit switch member 429 of limit switch assembly 254, first normally open relay contacts D430, second normally closed relay con- 8 tacts F432, a normally closed switch member 434 and a relay coil G436.

Another conductor 438(10) having first normally open relay contacts G440, a normally closed limit switch 244 and a switch member 442 of a first selector switch assembly 444, has one end connected to conductor 412 at a point between pressure switch assembly 248 and switch member 424, and its other end connected to conductor 412 between normally closed relay contacts F432 and normally closed switch 434. Branch conductors 446 and 448 are each so connected as to have their respective one ends connected to conductor 412 at opposite sides of relay contacts D430, and their respective other ends connected to conductor 438 on opposite sides of switch member 439 of limit switch assembly 244.

Switch assemblies 422 and 426 respectively have normally open switch members 450 and 457 which are adapted to be placed at times in circuit with a conductor 454(11) which also has, serially connected therein, normally open relay contacts G456, normally closed relay contacts F458 and a relay coil H460. Another set of normally open relay contacts H462 are in parallel with relay contacts G456 by means of a conductor 464.

A second selector switch assembly 466 has a switch member 468 in circuit with a conductor 470(12) which also in circuit therewith a second switch member 472 of selector switch assembly 444. Serially between switch member 468 and conductor 322 is situated a normally closed switch 474 while serially between switch member 472 and conductor 324 are situated normally open relay contacts H476 and relay coil C478. Another conductor 480, placed generally in parallel with switch member 472 and relay contacts H476, contains a first normally closed set of relay contacts F482 and a normally open set of relay contacts K484. A branch conductor 486 has its opposite ends connected to conductors 470 and 480 so as to be between switch member 472 and contacts H476 and between contacts F482 and K484.

Conductor 382(14) in addition to being connected to switch member 245 of limit switch assembly 244, also has serially connected therewith a switch member 490 of a second pressure switch assembly 250 (also see FIG. 3), a set of normally open relay operated contacts C494 and a winding 496 of a timer assembly L492. A branch conductor 498 is connected at one end with conductor 382 and, at its other end, connected to conductor 380 containing a switch member 502. A second branch conductor 506, containing a timing motor 504 and a switch member 500, is connected at its opposite ends to branch conductor 498 and conductor 382 between coil 496 and main conductor 324. A pair of normally open timer operated contacts L510(15), in conductor 508, are connected to conductor 382 so as to be in parallel with switch member 490.

Switch member 512 of selector switch assembly 466 is adapted to be at times placed in circuit with conductor 374(17) which also has, in circuit therewith, switch member 528 of pressure switch assembly 250, a set of normally open relay operated contacts D514, a second set of normally open relay operated contacts H516, a third set of normally open relay operated contacts G518 and relay coil E372.

A third switch member 524 of selector switch assembly 466 is adapted to be at times placed in circuit with conductor 526 (18) which has its opposite ends connected to conductor 374 in a manner placing conductor 526 in parallel with switch member 512, and contacts D514 and H516. A branch conductor 530 interconnects conductors 374 and 526 in a manner whereby one end is between switch member 524 and timer operated normally open contacts P522 in circuit with conductor 526. The other end of conductor 530 is connected to be between contacts D514 and H516.

Conductor 532(19) contains switch member 534 of limit switch assembly 254, a set of normally open relay operated contacts E536 and winding 538 of a second timer assembly P520. A branch conductor 540 is connected at one end with conductor 532 and, at its other end, connected to conductor 550(20) containing switch member 554 and a relay coil F552. A second branch conductor 548, containing a timing motor 546 and a switch member 542, is connected at its opposite ends to branch conductor 540 and conductor 532 between winding 538 and main conductor 324.

The circuit described above operates generally as follows.

Switch 306 is closed energizing conductors 92, 94, 96 and primary winding 316 of transformer 314. Next, if the automatic mode of operation is desired, selector switch 444 is moved to the automatic, A, setting causing switch member 442(10) to open and related switch member 472(12) to open.

The power switch assembly 386() is then pulled up causing both switch members 388 and 390 to be closed. This causes relay coil A392 to be energized resulting in contacts A308, A310 and A312, in conductors 92, 94, 96, to be closed energizing spinner motor 90. At the same time contact A394(6) are closed by relay A392 and relay coil B350 energized. Indicator lamp 400 is lit thereby providing a visual signal that the power is on in the circuit. Energization of relay B350 causes closure of relay contacts B346, B348, B354 and B356 respectively located in conductors 326, 328, 322 and 324. Releasing the power switch assembly 386(5) does not interrupt the circuitry because switch member 388 remains closed and current is carried through the then closed relay contacts A394 in conductor 352. It should be remembered that at this time pressure source 78 (FIG. 3) is supplying actuating pressure to conduits 202, 204 and 206 and that pressure switch 248, in conduit 226, is responsive to the air pressure therein. Accordingly, when the air pressure with conduit 226 is sensed by the pressure switch assembly 248 to be within predetermined prescribed limits, the normally closed switch member 404 opens and the related normally open switch member 410 closes. Further, it the air pressure should exceed the prescribed limit, normally closed switch member 414 is opened and the normally open switch member 416 is closed thereby opening the circuit through conductor 412(9) and energizing lamp 420 in conductor 418 to visually indicate excessive air pressure. Energization of lamp 408 in conductor 406 would, of course, indicate the existence of an air pressure below the predetermined required minimum.

At this time, with switch assembly 444 in the automatic mode, member 442(10) is open; however, switch members and relay contacts 410, 414, 424, 428, 429', 439, F432 and 434 in conductor 412 are closed thereby energizing relay 6436(9) which, in turn, closes contacts G440 in conductor 438, contacts G456 in conductor 454(11) and contacts G518 in conductor 374(17).

In order to start the cycle, the cycle-start palm button switch assemblies 422 and 426 are depressed causing members 424 and 428 to open while switch members 450 and 452 close completing the circuit through conductor 454 energizing relay H460; this, in turn, causes relay contacts H462 in conductor 464(11), H476 in conductor 470(12) and H516 in conductor 374(17) to be closed. Ideally, for safety purposes, palm switch assemblies are resiliently biased as to require the operator to maintain his hands on the switches during the cycle thereby assuring that the placement of his hands will be in a safe area and out of possible injury by the machine.

With the selector switch assembly 466 in the, C, or clamp position, contacts or switch members 468(12) and 512(17) are closed while switch member 472(12) of selector switch 444 is open. Accordingly, a circuit is completed through switch member 470, member 468, conductor 480, relay contacts F482, branch conductor 486 and closed relay contacts H476 energizing relay C478. Energization of relay coil C478, in turn, causes closure 10 of relay contacts C494 in conductor 382(14), and relay contacts C364 and C366 in conductor 332(2) thereby energizing solenoid 358 (also see FIG. 3) causing solenoid valve 242 to move to the right thereby establishing communication between conduits 240 and 82 and communication between conduits 84 and the atmosphere. Consequently, pressure is communicated to the top of cylinder assembly 40 and pressure switch assembly 250. This causes piston 134 of cylinder assembly 40 to move downwardly causing corresponding movement of clamping rod 138. When the clamping rod 138 becomes seated against the workpiece as shown in FIG. 3, the actuating portion of limit switch assembly 244, as schematically shown in FIG. 3, is engaged by any suitable portion of the piston 134, clamping rod 138 or interconnected structure moveable therewith in a manner well known in the art, causing switch member 243 of limit switch assembly 244(14) to become closed. At this time high pressure is being supplied through conduits 222 and 232. Branch conduit 234 senses the high pressure causing selector valve 238 of selector valve assembly 230 to be in the position illustrated in FIG. 3. Such pressure sensed by pressure switch assembly 250 causes switch member 490 to then complete the circuit through conductor 382( 14) energizing coil or winding 496 in timer assembly L492. The timer motor 504 is thusly energized, contact 500 being normally closed, and maintained so for a predetermined length of time during which the first relatively high clamping force is being applied by clamp rod 138 against the components of the workpiece.

After a first predetermined length of time, motor 504 of timer assembly L492 opens switch member 500 and closes switch member 502(15) thereby energizing relay coil D378(15); this, in turn, closes normally open relay contacts D376 in conductor 334(3), relay contacts D558 in conductor 556(16) and contacts D514 in conductor 374(17).

The closure of relay contacts D376(3) results in the energization of solenoid 360 (FIG. 3) which moves solenoid valve 229 to the right so as to block or close conduit 222 while venting conduit 232 to the atmosphere. Consequently, the pressure in conduit 234 is vented permitting the relatively low pressure in conduits 224 and 236 to shift selector valve 238 to the left thereby completing communication between conduits 224 and 82. As a result of this, the piston 134 of cylinder assembly 40 continues to apply a substantial force to the clamping rod 138; however this force is less that that initially applied during the period that timer L492 was operating with switch 502 open. When this second lesser pressure is sensed by the pressure switch assembly 250 the normally open switch member 528 is closed thereby completing the circuit through conductor 37 4( 17 switch member 528, normally closed switch member 512, closed relay contacts D514, H516, G518 and relay coil E372.

Energization of relay coil E372 causes closure of relay contacts E368 and E370 in conductor 336(4) which contains, in series therewith, solenoid coil 362 (also see FIG. 3). Energization of coil 362 of solenoid valve assembly 246 causes solenoid valve 252 to be moved to the right thereby completing communication between conduits 226 and 88 while venting conduit 86 to the atmosphere. Consequently, piston 256 of cylinder assembly 50 (and of cylinder assembly 48 if two are employed as shown by FIGS. 1 and 2) is actuated causing the spindle assembly ot be fed downwardly, as by means of linkages 74, 62, end cap 66, shaft 68, gear 72 and cooperating rack 120. Switch member 429(9) of limit switch 254 is held closed until spindle 112 is moved downwardly seating the spinner rollers 124 and 126 of spinner assembly 122 against the workpiece 142.

When the spinner assembly 122 is thusly seated, limit switch member 429(9) is opened while limit switch member 534 of limit switch assembly 254(19) is closed and since relay contacts E536 were previously closed by the relay coil E372(17) the circuit through winding 538 and motor 546 of a second timer assembly P520 is completed. The spinner rollers 124 and 126 are of course being rotated by motor 90 and the spinner rollers are continually being forced against the workpiece for a predetermined length of time after which motor 546 causes switch member 542 to open and switch member 544 to close. This results in the energization of relay coil F552(20) which causes normally closed relay contacts F432(9) in conductor 412 and normally closed contacts F458 in conductor 454(11) to open. At this tim switch member 429(9) is open, selector switch member 442(10) is open and relay contacts F32 are opened; this results in the deenergization of relay coil G436 causing the opening of all the relay contacts related to relay G436. Such relay contacts are located in conductors 454(11) and 374(17) and the opening thereof causes the circuit through such conductors and relay coils H460(11) and E372(17) to be opened. As can be seen from the previous description and the drawings there is a somewhat sequential cascading effect resulting in the de-energization of relay coils C478, D378 and F552 causing corresponding opening of related relay-actuated contacts thereby reversing shifting solenoid valve assemblies 208, 228 and 246 (FIG. 3) so as to return the respective pistons 134 and 256 to their start-of-cycle positions.

With the selector switch 444 in the manual mode of operation, it can be seen that switch member 442 is closed thereby bypassing contacts F432(9). Therefore, spinning of the spinning assembly 122 will continue against the workpiece until the spindle return switch 434(9) is depressed causing the de-energization of relay G436 and subsequent opening of contacts as discussed above.

If the unclamp or no-clamp (NC) mode of operation is desired and the selector switch 466 is moved to the NC position, contacts or switch members 468 and 512 are opened while switch member 524 is closed. As is apparent, the effect of this is to eliminate the clamping function out of the overall operation. This might Well be of advantage during machine set-up or tooling tryouts.

In view of the above, it can be seen that a novel method and apparatus has been invented whereby jointed structures having predictable physical characteristics can be repeatedly produced.

Certain details have been omitted from one or more figures for purposes of clarity. For example, the limit switch assemblies 244 and 254 have not been illustrated in FIGS. 1 and 2 but shown schematically in FIG. 3 since the actual placement on the machine is a matter of choice and well within the ability of one skilled in the art. All that is required is that suitable tripping dogs, surfaces or abutments on or associated with the clamping rod 138 and spindle 112 be provided in order to engage and actuate the respective limit switches in the manner described herein.

Further, it should be pointed out that the invention herein disclosed has specifically taught the concept that the initial high preload force may be applied for a predetermined length of time, that the subsequently lesser preload force is applied during the spinning or metalforming portion of the cycle which portion is also determined in terms of a span of time. However, it should be apparent that other indicia of cycle completion or completion of a particular portion of the cycle may be equally Well employed. For example, it is conceivable that during the spinning operation, the linkage could be rotated relative to the seat carried by the housing and that when a certain resistive torque was experienced by the means rotating the linkage that this could be employed as a signal for terminating the spinning portion of cycle.

Although basically only one preferred embodiment of the invention has been specifically disclosed and described, it is apparent that other embodiments and modifications of the invention are possible within the scope of the appended claims.

I claim:

.1. A method of fabricating a jointed structure having at least a housing with at least one open end, a seat portion carried by said housing, a linkage member adapted to engage said seat portion in a generally mating manner and a retainer situated within said housing generally within said open end, comprising the steps of applying a first relatively high preload force of a first predetermined magnitude against said linkage member and said housing in order to force said linkage member against said seat portion, dissipating said first preload force and applying at least a second relatively low preload force of a second predetermined magnitude less than said first predetermined magnitude against said linkage member and said housing in order to maintain said linkage member against said seat position, and forming at least the material comprising said housing in at least the vicinity of said retainer in order to hold said retainer in a prescribed position relative to the housing and linkage in order to provide for a certain degree of freedom of relative movement between the linkage and housing.

2. A method of fabricating a jointed structure according to claim 1 wherein the step of forming at least the material comprising said housing in at least the vicinity of said retainer is performed while said second relatively low preload force is being applied.

3. A method of fabricating a jointed structure according to claim 1 wherein said first relatively high preload force is applied for a predetermined span of time.

4. A method of fabricating a jointed structure according to claim 1 wherein said first relatively high preload force is applied for a predetermined span of time and wherein said second relatively low preload force is applied for a second predetermined span of time.

5. A method of fabricating a jointed structure according to claim 1 wherein the step of forming at least the material comprising said housing includes cold-Working of said material in order to at least partially envelop the peripheral portions of said retainer.

6. A method of fabricating a jointed structure according to claim 1 wherein the step of applying said first relatively high preload force against said linkage member and said housing includes the application of said first relatively high preload force to said retainer, and wherein the step of applying said second relatively low preload force against said linkage member and said housing includes the application of said second relatively low preload force to said retainer.

7. A method of fabricating a jointed structure according to claim 6 wherein the step of forming at least thematerial comprising said housing in at least the vicinity of said retainer is performed while said second relatively low preload force is being applied.

:8. Apparatus for fabricating a jointed structure having at least a housing with at least one open end, a seat portion carried by said housing, a linkage member adapted to engage said seat portion in a generally mating manner and a retainer situated within said housing generally within said open end; comprising first means for holding said housing, linkage member and retainer; a force transmitting member adapted to at times be generally applied against said housing, linkage member and retainer; second means effective for at times applying a first force of relatively high magnitude through said force transmitting member to said housing, linkage member and retainer; third means effective for at other times causing said second means to apply a second force of relatively low magnitude through said force transmitting member to said housing, linkage member and retainer; and tool-carrying means adapted to carry suitable material-forming tool means for causing said tool means to engage at least said housing and cold work at least the material comprising said housing in order to hold said retainer in a prescribed relationship to said housing and linkage member.

9. Apparatus for fabricating a jointed structure according to claim 8 wherein said second means comprises pressure responsive motor means, and wherein said third means comprises valving means and associated conduitry effective for terminating communication of a first relatively high pressure actuating fluid to said pressure responsive motor means and completing communication of a second relatively low pressure actuating fluid to said pressure responsive motor means.

10. Apparatus for fabricating a jointed structure according to claim 8 wherein said tool-carrying means comprises a rotating spindle-like assembly axially movable toward and away from said first means, and including second pressure responsive motor means operatively connected to said spindle-like assembly, said second pressure responsive motor means being effective upon the application of suitable fluid pressure thereto to move said spindle-like assembly toward said first holding means for causing said tool means to engage at least said housmg.

11. Apparatus for fabricating a jointed structure according to claim 8 wherein said tool-carrying means comprises a rotating spindle-like assembly axially movable toward and away from said first holding means, wherein said force transmitting member comprises an elongated rod axially aligned with said spindle-like assembly and extending therethrough, wherein said second means comprises pressure responsive motor means operatively connected to said elongated rod, wherein said third means comprises valving means and associated conduitry operative for at times terminating communication of a first relatively high pressure actuating fluid to said pressure responsive motor means and competing communication of a second relatively low pressure actuating fluid to said pressure responsive motor means, including second pressure responsive motor means operatively connected to said spindle-like assembly and being effective upon the application of suitable fluid pressure thereto to forceably move said spindle assembly toward and away from said first holding means, and including timer means for determining the span of time during which said first relatively high pressure actuating fluid is directed to said first-mentioned pressure responsive motor means and for determining the span of time during which said second relatively low pressure actuating fluid is directed to said firstmentioned pressure responsive motor means.

References Cited UNITED STATES PATENTS 3,444,606 51/ 1969 Jones 29-200 THOMAS H. EAGER, Primary Examiner U. S. Cl. X.R. 

